Rotary drill bit



"Sept. 1-7. 1940. v 8.1. I HER 2 215 26 ROTARY DRILL an and am. 16. 1933faaezer 17.5452

Patented Sept. 17, 1940 PATENT OFFICE ROTARY DRILL BIT Robert P. Fisher,Los Angeles, Calif., assignor to Rudolph Pageman, Compton, Calif.

Application-November 16, 1938, Serial No. 240,677

13 Claims.

This invention relates to drill bits for the rotary drilling of boreholes, such as oil wells, being particularly concerned with themanner inwhich the cutters are rotatably mounted and carried by the bitstructure.

In a widely used type of roller drill bit, depending arms are providedto support a transversely extending shaft device carrying roller cuttingelements designed to remove the central portion of the formation beingoperated upon. Detrimental deflection of the shaft device has beenavoided heretofore by providing an intermediate bridge support. However,such constructions reduce the digging effectiveness of the bit since thecutters do not extend along the whole length of their shaft device,being interrupted by the bridge and either leaving a core at the centerof the hole, which retards drilling progress, or requires that onecutter do the major share of the digging, as in constructions in whichthe bridge is offset to one side of the center line of the bit.

It is an object of this invention to provide a bit having a transverselyextending shaft device free from detrimental deflection, such freedombeing 25 obtainable without 1 the use of an intermediate supportingbridge.

A further object of the invention is to provide a rigid shaftconstruction in a drill bit having cutters extending substantially alongthe entire length of the shaft; thus preventing the production of a corein the hole, and equalizing the work done by the cutters.

Still another object of the invention is-to provide an improved bearingmounting for the cross cutters of a rotary drill bit.

Another object of the invention is to eliminate lost motion or end playbetween roller bit cutters and their supporting bearing parts.

A further object of this invention is to provide 40 a simple expedientfor insuring snug bearing engagement between rolling bearing elementsvand the cutters of a drill bit. 2

Another object of the invention is to provide a sturdy rotary bitconstruction, economical to manufacture, and easily assembled anddisassembled.

This invention possesses many other advantages, and has other objectswhich may be made more easily apparent from a consideration of one 50embodiment of the invention. For the purpose of illustration, one formof the invention is shown in the drawing accompanying and forming partof the present specification. This form will now be described in'detail, illustrating the general 55 principlesof the invention; but it;is-to be understood that this detailed description is not to be taken ina limiting sense, since the scope of the invention is best defined bythe appended claims. I Referring to the drawing:

. Figure l is a sectional view, parts being shown is bifurcated toprovide branches 23, 23 between in elevation, of .a roller drill bitembodying the invention;

Figure 2 is a partially sectional viewt oi' the drill bit, taken alongthe line 2-2 of Figure 1;

Figure '3 is a front elevation as seen along the 5 plane 3-3 of Figure1; and

Figure 4 isaperspective of part of the bit device, elements beingshown'separated for purposes of clarity.

The drill bit disclosed in the drawing includes 10 a main supportingbody or shank Ill having a threadedpin, H at its upper end forattachment of the tool to-a drilling string (not shown). De-'- pendingfrom the shank are a pair of integral legs l2, l2 rotatably carryingside cutter rollers 15 l3, l3 which can remove the outer portion of theformation in the hole being operated upon. The shank. III also carriesthe cross roller cutters l4, l4 ithrough suitable supporting and bearingmechanism to be described hereinafter. These 0 cutters serve to removethe remaining, central portion of the formation material at the bottomof the hole. l

The side roller cutters l3, I3 are rotatably supported on bearingsupporting members l5, I5, 25 each having a. web 16 abutting an inclinedthrust 1 surface II on a cooperative leg l2, with side wings l8cooperating with the sides of these legs. The outer ends of the wings Hican bewelded to the outer surface of each leg to secure the bearing 30supporting member to the shank. Details of construction of this portionof the bit are both claimed and described in my. co-pending applicationsRotary drill bit, Serial No. 190,444, filed Feb. 14, 1938; Rotary drillbits, Serial No. 201,750,

filed April 13, 193.8; and Roller bit bearing, Serial No. 226,950, filedAug. 26, 1938. It is to be understood, howeve that. other modes ofmounting and supporting the side roller. cutters l3 than the onespecifically indicated can be used with out affecting thescope of theinvention now to be described. H

The cross cutter rollers l4, l4 are supported from a cutter carrier 19having an upper plate portion20 abutting against a surface 2| of theshank extending between a recess partly defined by the dependingintegral legs 12, I2. Depending from the abutting shank portion of thecutter carrier are a pair of. arms 22, 22 each of which which arereceived a supplementary arm or bracket 24. The upper end 25 of eachbracket 24 is stepped to overlap an arm rib 26 extending between thebifurcations 23, 23 and forming with those portions a recess 2'lreceiving the stepped bracket portion 25. The lower end of the bracketis provided with a generally cylindrical end thrust bearing or boss 28abutting against the side surfaces 29 of the bifurcations 23. The upperpart 25 of the bracket therefore engages R0 Inwardly directed endthrusts are transmitted from the cutters to the transverse shaft byproviding an enlarged central flange 34 on the shaft which has formed inits outer faces raceways 35 for receiving the bearing balls 36, thelatter also being rollable in complementary raceways 31 formed at theinner ends of the cross roller cutters.

The cross cutter rollers i 4, i4 and their associated bearing andsupporting parts can be assembled by placing an inner set of bearingballs 33 on the central flange raceway '35 and a set of roller bearings32in one of the cutters. The cutter with the roller bearings in positionis then placed over this shaft, its inner raceway 31 abutting the innerset of bearing balls 36. The outer set of bearing balls 33 is thenplaced in the outer cutter bearing raceway 38 and the supplementary armor bracket 24 threaded onto the end of the transverse shaft until itsraceway 39 engages this outer set of balls and end play or lost motionis eliminated by the snug but freely rolling engagement of the ballswith their cooperative raceways. The other cross cutter and its bearingsand bracket can be assembled on the other end of the shaft in a similarmanner. I 2

' This assembly is then placed between the arms 24, 24 of the cuttercarrier IS with the outer surfaces 28a of the bearing bosses 28engageable with the inner portions 29 of the bi- .furcations and theupper parts 25 of the supplementary arms or brackets 24. abuttingagainst both the outer faces 26a. and the beveled under faces 28b of theribs. The brackets 24 can then be rigidly secured to the cutter carrierl9 by welding in material 40 in a groove formed between each bracket andthe arm bifurcations 23, 23. If deemed essential, the ends of thetransverse. shaft can also be welded-to the supplementary arms 24 at theouter region of the threaded bore 30.

The upper portion 20 of the cutter carrier I9 is provided with slots 4|communicating with a. shank passageway 42, in order to direct drillingmud or other liquid upon the cutters to clean.

sessing great resistance to bending and deflection. Such resistance isoffered by the shaft itself, since the provision of the enlarged centralflange 34 makes it possible for the shaft to carry safely a greaterbending moment than if the shaft possessed its smaller roller bearingdiameter along its whole length. In addition to adding to the resistanceto bending, the central flange 34 also offers a simple expedient fortransmitting inwardly directed end thrusts directly from the cutters tothe'shaft, preventing-a rubbing action between the end faces of thecross cutters. Outwardly directed end thrusts are transmitted to thebracket bosses 28, from where they will pass directly to the carrierarms 22 in view of the abutting relationship between their innersurfaces 29-and the bosses. Axial motion by the cutter along its shaftin either direction is thereby prevented, increasing the life of thebearings and of the drilling bit as a whole.

I claim:

1. A roller bit for drilling bore holes including a supporting body, apair of spaced arms depending from said body, a shaft extending betweenand carried and supported only by said arms, said shaft having a centralflange between its ends, cutters rotatably mounted on said shaft alongtheir entire length and supported substantially entirely thereby, and aplurality of balls between each cutter and said flange for transsaidflange being of still greater diameter to increase the rigidity of theshaft.

2. A roller bit for drilling bore holes includ ing a supporting body, apair of spaced arms depending from said body, a shaft extending betweenand secured to said arms, said shaft having a central cylindrical flangebetween its ends, a cutter rotatably mounted on said shaft between saidflange arid one of said arms, a. second cutter rotatably mounted on saidshaft between said flange and the other arm, rolling bearing elementsbetween said cutters and said flange and also between the outer ends ofrespective cutters and said arms for transmitting end thrusts, saidcutters overlapping said flange about its entire circumference andsubstantially along its entire length, whereby said cutters areoperative upon the formation at the axis of the bore.

3. A roller bit for, drilling bore holes including a supporting body, apair. of spaced arms depending from said body, a straight shaftextending between said arms and threadedly secured thereto, said shafthaving a central cylindrical flange between its ends, a .cutterrotatably mounted on said shaft between said flange and one of saidarms, a second cutter rotatably mounted on said shaft betweensaid'fiange and the other arm, said flange being provided with racewaysin its side faces, ra'ceways in the ends of said arms and at both endsof each cutter, and balls in said raceways between the inner ends ofsaid cutters and said flange and also between the outer ends ofsaid'cutters' and said arms for transmitting end thrusts, the inner endsof said cutters overlapping said flange about its entire circumferenceand substantially along its entire length, whereby said cutters areoperative upon, the formation at the axis of the bore. I

4. A roller bit including a supporting body, a plurality of spacedbifurcated arms depending from said body, a supplementary arm flxed toeach arm and positioned between its bifurcations, a shaft extendingbetween and secured to said supplementary arms, said shaft having a l0ters rotatably mounted on said shaft,

ters and said flange and bosses.

flange between its ends for increasing its resistance to bending, andcutters rotatably mounted on said shaft between its flange andsupplementary arms.

5. A roller bit including a supporting body, a plurality ofspaced-bifurcated primary arms depending from said body, a supplementary.arm fixed to each primary arm and positioned between its bifurcations,each supplementary arm having an upper portion in overlapping engagementwith an outwardly facing primary arm portion and a lower boss inoverlapping engagement with inwardly facing primary arm bifurcations, ashaft extending between and secured to said supplementary arms with itsends within said bosses, said shaft having a flange between its ends,cutters rotatably mounted on said shaft, and means for transmittingbearing loads between said cutters and said flange and bosses.

6. A roller bit including a supporting body, a pair of bifurcatedprimary arms depending from and detachably secured to said body, asupplementary arm fixed to each primary arm and positioned between itsbifurcations, a shaft ex-. tending between and secured to saidsupplementary arms, and cutters rotatably mounted on said shaft.

,7. A roller bit including a supporting'body, a pair of bifurcatedprimary arms depending from said body, a supplementary arm flxed to eachprimary arm and positioned between its bifurcations, each supplementaryarm having an upper portion in overlapping engagement with an outwardlyfacing primary arm portion and a lower boss in overlapping engagementwith inwardly facing primary arm bifurcations, a shaft extending betweensaid arms with its ends threadedly received within said bosses, saidshaft having a central flange between its ends, cut

' sai bosses, cutters and flange being provided with end raceways, androlling elements in said raceways for transmitting bearing loads betweensaid cutters and said flange and buses.

8. A roller cutter assembly including a shaft having a cylindricalflange intermediate its ends, an arm threaded onto each end of saidshaft, each arm having an inwardly directed boss, a cutter rotatablymounted on said shaft between its flange and each boss, raceways in theends of each boss, cutter and flange, and rolling elements in saidraceways for transmitting bearing loads between said cutters and saidflange and bosses.

9. A roller bit including a main body, a, cutter carrier detachablysecured to said body, said carrier having a pair of depending primarybifurcated arms, a supplementary arm fixed to each primary arm andpositioned between its bifurcations, each supplementary arm having anupper portion in overlapping engagement with an outwardly facing primaryarm portion and a lower boss in overlapping engagement with inwardlyfacing primary arm bifurcations, a shaft extending between and securedto said supplementary arms with its ends within said bosses, said shafthaving a central flange, cutters rotatably mo ted on said shaft, andmeans between said cutror transmitting bearing loads 10. A I'Ollr bitfor drilling bore holes including a supporting b y, .a plurality of armsdeadjncent arm for transmitting pending'from said body, a shaftextending between and carried and supported only by said arms, saidshaft being of sufficient diameter throughout its length to withstandheavy loads imposed thereon, said shaft having a radially enlargedcentral stiffening flange between its ends and a raceway on each side ofsaid flange extending substantially from said flange to one I of saidarms, a cutter rotatably mountedpn said shaft on each side of saidflange and overlapping said flange about its entire circumference andsubstantially along its entire length,

whereby said cutters are operative upon the.

formation at-the axis of the bore, and rolling bearing elements betweeneach shaft raceway and an associated cutter for transmittingsubstantially all radial bearing loads therebetween.

11. A roller bit including a-supporting body, a pair of spaced armsdepending from said body, a unitary shaft extending between and carriedby said arms, said shaft having a flange between its ends and a radialbearing raceway on each side of said flange extending substantially fromsaid flange to one of said arms, a cutter rotatably mounted on saidshaft on eachside of said flange, roller bearings between each of saidcutters and an associated raceway, and ball bearings between each cutterand flange.

flangeextending substantially from saidflange to one of said arms, acutter rotatably mounted on said shaft on each side of said flange andoverlapping said flange about its entire circumference and substantiallyalong its entire length,

whereby said ,cutters are operative upon the formation at the axis.ofthe bore, rolling hear- :ing elements between each raceway and anassociated cutterfor transmitting substantially all radial bearing loadstherebetween, rolling bearing elemerits between the inner endof eachcutter and flange for transmitting axial thrust in one direction, androlling bearing elements between the outer end of each cutter and anaxial thrust in the other direction. 13. A roller bit for drilling boreholes including a supporting body, a plurality of spaced arms dependingfrom said body, a shaft extending between and secured to said arms, saidshaft having a central cylindrical flange between its ends and a rollerraceway on each side of said flange extending substantially from saidflange tonne of said arms, a cutter rotatably mounted on said .shaft. oneach side of said flange and way between the inner and outer ends ofeach cutter for transmittingradial bearing loads between said cutter andraceway.

ROBERT P. FISHER.

along its entire length,-

